2 x 5870 won't boot in Bootcamp but 1 x5870 will (either one)

Pulling my hair out over this one,

i have a mac pro 2.1 dual quad core 3ghz, 6gb ram, 2x500gb HD originally came with X1900 XT and installed bootcamp windows 7 64bit.

Ran flawlessly.

bought an ASUS flashed Radeon HD5870. installed the card and installed AMD catalyst control centre and drivers, the 5870 in PCie slot 1 and ran flawlessly in both OSX and Win7.

in error i bought a second Flashed AMD Radeon HD5870 and a second psu,
i installed it into PCi-e slot 2 and changed the express slots to 8x for each card.
Boots perfect in mac and works perfectly, being able to see both 5870's in the System profiler.

now the problem begins.

If i boot with both cards into bootcamp, they both spool the fans, and win7 boots into something like 640x480 and catalyst control centre wont open, and both cards Aren't detected and do not show in computer management>device manager.

If i restart with an individual card (doesn't matter which one) windows 7 boots up perfectly fine, so both cards work fine individually in both slots 1 or 2. (so i have ruled out a hardware issue)

funnily enough, if i boot with a single 5870, put the computer to sleep once booted, insert and power up the second 5870 and wake the computer,
windows 7 then detects the second 5870 and installs drivers and can see both "AMD RADEON 5800 SERIES" in the device manager, BUT in order to use the hardware changes i must restart win7, which is impossible with both cards as it wont detect and just boot into 640x480 and drivers wont run.

i have a few questions.

1. Should i reinstall windows 7 from scratch with both 5870's installed?
2. Does windows auto detect when installing a new copy of win7?
3. Does bootcamp have some sort of Bios utility that i can assign PCi-e channels to slots like i can in OSX express/expansion utility?

i have searched every forum and thread and AFAIK no one has ever experienced this problem.

i wil post some photos up when i get home.


if you need any more information about my system etc ask,


EDIT: i also have not installed Apple Bootcamp drivers as i have heard that Crossfire wont work with them installed.

thanks,

Blaise

makaveli559m said:

I suggest you keep messing with the express/expansion utility until you find something that works.

Click to expand...

i am not sure if this is a PCI-e problem, i can get any card to work in any slot in osx together with any PCie channel config using the utility.

just windows cannot do both.

as stated before i have tried every single PCie combination possible,
i have Reflashed one of the cards to every single version of default BIOS that ATI has released (it seems that the last two revisions are mac compatible, would this mean that we no longer have to flash PC 5870's?)

and still no booting when both cards are installed,

it has to be something with windows and the booting process, i simply cannot get it to boot with two cards physically installed. about to smash this card into peices.

a Crossfire patch on the mac side to allow two cards to be used in bootcamp?

yeh i know crossfire is possible, and it would be possible on my mac as well if i could just get the thing to boot up with both cards in windows,

i read somewhere that there is no PCiE support for bootcamp or something?

another thing i noticed as well was i installed one 5870 and my original 1900XT and the same thing happened, no boot. just sits there with the flashing "_" in the top left hand corner and Fans go on full and the Cards heat up.

i tried reinstalling bootcamp with both cards in on the same Harddrive as my OSX and when it finished partitioning the HD and went to boot off CD. same thing happened, Blank screen, no boot.



GRRRRR. anyone wanna buy a Mac flashed 5870 and PSU?

Update, if i remove the harddrive with windows on it, but still have it selected to boot into windows, the same thing happens, just flashing underscore at the top. so this would tell me that both graphics cards installed cause my system to not see the Windows hard drive? right?

Dont worry about it anymore guys,

Fried the Card somehow while putting them both in plus my X1900,

funny thing is that it would boot, and see both 5870's yet i could only get video from the X1900 and that said the 1900 couldnt work because there were previous drivers installed or something, pulled the 1900 out live and now the 5870 wont boot or anything.

just going to trash them both and put in a 7970

anyhoo the 5870 is in peices on the road, thank you for your time.